1. Field of the Invention
The present invention relates to a recording tape cartridge rotatably housing a reel wound with a recording tape such as a magnetic tape.
2. Description of the Related Art
A recording tape such as a magnetic tape is used as an external recording medium for computers and the like. For the recording tape, a so-called single reel recording tape cartridge—whose housing space at the time of storage is small, in which a large amount of information can be recorded, and in which a single reel wound with a recording tape is rotatably housed inside a case—has been adopted.
In such a recording tape cartridge, a reel in which flanges are respectively disposed at both axial-direction ends of a reel hub wound with the recording tape is housed in a case formed by an upper case and a lower case being joined together so that mutual peripheral walls of the upper case and the lower case come into contact each other. When the recording tape cartridge is not in use, the reel housed in the case is in a state where the reel is pushed against the lower case by an urging force of a coil spring or the like. A gear opening for exposing a reel gear formed at an axial-direction lower end surface of the reel is disposed in the lower case.
When the recording tape cartridge is to be used, the recording tape cartridge is loaded into a drive device. A drive gear of the drive device meshes with the reel gear and causes the reel to rise inside the case counter to the urging force. The drive gear is then rotatingly driven, whereby the reel is made to rotate without contacting inner surfaces of the case. Thus, information can be recorded on the recording tape or played back by taking up or rewinding the recording tape through an opening in the case for pulling out the recording tape.
However, in the above-described conventional recording tape cartridge, it is possible for the reel to vertically move (rise and fall) inside the case. Thus, for example, there has been the problem that the reel ends up being inclined inside the case when a user mistakenly pushes the exposed reel gear or drops the recording tape cartridge.
In this instance, when the space inside the case is large in the vertical direction, the inclination (angle of inclination) of the reel becomes large. In a single reel recording tape cartridge, such a large inclination of the reel results in relative movement between the recording tape and the reel because a leader member disposed at an end portion of the recording tape is fixedly positioned inside the case in the not-in-use state. Thus, there is the potential for width-direction end portions (edges) of the recording tape to contact the flanges of the reel and sustain damage. The same problem occurs even in two-reel recording tape cartridges.
Although it is conceivable to thin the thickness of the case as a countermeasure therefor, this is unrealistic because the thickness of the case is determined on the basis of the specification and the demand from the drive device. Alternatively, if the thickness of the case is thickened in order to narrow the vertical dimension of the interior space, the moldability of the case, which is usually formed by resin molding, deteriorates and this deterioration leads to an inferior appearance. Additionally, thickening the thickness of the case results in an increase in the amount of resin used, an increase in the weight of the case, and an increase in costs.
Thus, in order to suppress inclination of the reel, disposing ribs that partially project from the inner surfaces of the case has been considered. For example, a configuration in which plural ribs are disposed in a radial manner at an inner surface of a lower case configuring a case is described in Japanese Patent Application Laid-open Publication (JP-A) No. 9-45034, even though this configuration relates to a two-reel recording tape cartridge. However, the ribs disclosed in this publication are for reducing the amount that the reel rises with respect to the lower case. Because the ribs are not disposed at the upper case, the effect with respect to suppressing inclination of the reel is small.
Configurations in which annular or arced ribs coaxial with the reel are respectively disposed at the upper and lower cases, and configurations in which plural ribs that differ in number between the upper and lower cases are respectively disposed in a radial manner, are being adopted in actual products. However, none of these configurations can effectively regulate inclination of the reel.
Thus, in the field of recording tape cartridges, there is room for improvement in relation to ribs for suppressing inclination of the reel, and particularly in relation to the disposition of the ribs.
In consideration of the above-described facts, it is an object of the present invention to obtain a recording tape cartridge that can suppress inclination of a reel, with ribs vertically disposed inside a case.